Additional Study Information: The study is being done to see if the combination of bendamustine and dexamethasone will help people with amyloidosis that has returned after standard treatment. Bendamustine is currently approved by the Food and Drug Administration (FDA) for treatment of chronic lymphocytic leukemia (CLL) and is under clinical development in the United States for the treatment of non-Hodgkin lymphoma (NHL). Dexamethasone is a synthetic (man-made) steroid with powerful anti-inflammatory effects. It can also alter your body's immune response. ClinicalTrials.gov: http://clinicaltrials.gov/ct2/show/NCT01222260